1. Field of the Invention:
This invention relates to an improved method of bleaching in aqueous systems such as laundry operations, processing of textile materials, or fabric goods using a mixture of chlorine- and bromine-containing compounds at lower temperatures and shortened time intervals.
2. Prior Art:
The use of halogen-releasing agents for bleaching in aqueous solution, as part of the processing or laundering of textile materials, is well known. Traditionally, chlorine-containing bleaching agents have been preferred because of their bleaching ability, relative low cost and acceptable odors. Examples of such chlorine-containing bleaching agents include chlorine gas, alkali metal hypochorites and organo-chlorine complexes.
Most chlorine bleaching agents employed in laundering or processing textile materials require temperatures of approximately 160.degree. F. to effect adequate bleaching. Reduction in process temperature is desirable for the associated energy savings. To this end, it has been found that supplementing chlorine bleaching agents with bromine-containing compounds in a highly alkaline solution provides effective bleaching at lower temperatures. To accomplish effective bleaching, low temperature bleaching methods require large concentrations of bromine-chlorine bleaching compounds. The textile material or fabric to be bleached is exposed to high concentrations of halogen ions.
Extended periods of contact between aqueous bleaching agents in high concentrations and the textiles to be treated destroys fabric integrity, reduces the useful life of the fabric, and causes discoloration. To date, no bleaching method has been developed which produces effective whitening in shortened bleaching intervals.
Bleaching which occurs in highly alkaline aqueous media can have similar detrimental effects on fabric durability and appearance. Thus, a bleaching process in which equivalent cleaning and whitening could be accomplished in shortened time periods requiring less halogenated bleaching agent, is highly desirable. Thus, it would be desirable to provide a method of bleaching fabrics and other materials at or near a solution pH of 7.
It is also desirable to provide a bleaching method which can occur at lower process temperatures.